get_header_image_tag() should use alt text defined by users in media library and not generic get_bloginfo('name')

[RedBMedia]

Currently get_header_image_tag() creates alt text by simply calling get_bloginfo('name'). This doesn't seem to serve the purpose of alt text in many cases. Therefore alt text should be taken from the image's media library entry set by the user.

Also allowing for this alt text to be called separately with an additional arg would help developers that are forced for create banner images with CSS but still want to provide the appropriate aria-label for the div.

[SergeyBiryukov]

Hi there, welcome to WordPress Trac!

Thanks for the report, we're already tracking this issue in #46124.